had screen repaired on iphone 6s forgot apple id and passcode, can not activate phone

See if you can recover the ID/password.

Apple ID - How to find your Apple         An iCloud e-mail address is an Apple ID.

Apple ID - Find

Enter the Apple (iCloud) ID and click Forgot Password.

Apple ID - Manage

Apple ID – Forgot Password

If you forgot the passcode.

Passcode - If you forgot the passcode for your iPhone, iPad, or iPod touch, or your device is disabled

If necessary, if you are the original owner, take the device, the original purchase receipt with the serial number, and a photo ID to the nearest Apple Store.

Genius Bar Reservation US

or contact Apple ID Support. They will need to see the original purchase receipt/paperwork also.

Apple ID Support

Apple ID Support (2) 

Apple Support by e-mail or chat         

Apple Support using Twitter

Or fill out and submit this form.

Did you try the links I posted above to recover the ID?